Nephrolithiasis or stones in a kidney of a human patient is a common condition which can be quite painful and injurious to the kidney if the stone does not pass naturally. Some stones are quite small and begin to flow through the ureter or tube from the kidney to the bladder with natural flow of fluid from the kidney. Although the moving stone can be quite painful, its ultimate passage from the kidney to the bladder does not require any surgical or medical intervention. In other instances, a stone may be small enough to pass into the ureter and become lodged at a position low enough that a mechanical basket or other mechanical manipulator can be passed through the bladder, up the ureter for capturing the stone and mechanically extracting it. When the stone is lodged in the lower portion of the ureter, it is also possible to use catheters and various ultrasonic or vibratory impact devices for disintegrating the stone which can be reached by the catheter. These devices generally involve the use of an ultrasonic transducer as shown in Pohlman U.S. Pat. No. 3,927,675, Antonevich U.S. Pat. No. 3,861,391 and Kloz U.S. Pat. No. 3,792,701. Such impact disintegration devices must engage the stone and transmit disintegration energy to the stone through a transducer of some type located outside the body and connected to the location of the stone through an appropriate catheter extending through the normal urinary tract. These devices generally employ a cystoscope so that the doctor can manipulate the transducer through the catheter and into the appropriate physical relationship with the stone lodged inside the ureter. The transducers must direct enough energy to the stone by a single transducer; therefore, transverse energy losses are high and can cause some trauma. The time for disintegration can be long due to the inability of transmitting high energy. Other similar devices have been suggested for disintegrating stones by passage of a catheter and instruments through the bladder into the position adjacent the stone causing the physical difficulty. An electric discharge device is shown in Tessler U.S. Pat. No. 4,027,674. An explosive device is shown in Watanabe U.S. Pat. No. 4,196,736. A combined ultrasonic and physical grapling device is illustrated in Schwartz U.S. Pat. No. 4,046,150. All of these patents are incorporated by reference herein for the purpose of background information.
The devices and systems described above and shown in the prior art patents using cystoscopes, catheters and various mechanical devices can not be used for the situation when the stone occurs in the upper portion of the kidney and is too large to pass through the outlet tube or ureter into the bladder or into the lower portion of the ureter where it can be reached from outside the body. The existence of a stone lodged in the kidney which can not, or does not, pass from the kidney can cause blockage and requires removal, sometimes on an emergency basis. In the past, the only system or method generally used for removing such stones lodged in the kidney was a surgical procedure wherein the patient was generally anesthesized and an incision was made through the body and into the kidney itself by surgical instruments so that the stone could be visually exposed and manually removed with appropriate instruments. This surgical procedure required a substantial amount of recuperation primarily because of the trauma resulting from the large incision required to reach the remote body area where the kidney is located. An incision in the kidney or the outlet of the kidney and through the heavy muscular portion of the patient required a substantial recuperation time, lengthy discomfort and the normal risk involved in any major surgery.
In recent years two medical developments have been made to simplify the removal of a stone lodged in the kidney, or other body organ, when the stone causes infection, blockage or other serious situation and is too large to pass simultaneously from the organ through the normal body passages. The first system is percutaneous nephrotomy combined with dilation of the surgical passage into the kidney and removal of the stone or renal calculus from the kidney. The second is generally referred to as extracoporeal ultrasonic lithotripsy. Both of these new procedures have evolved from normal advances in surgical and ultrasonic technology; however, they are not completely acceptable because of certain problems experienced with their use.
The percutaneous nephrotomy and dilation method involves the use of a radiographic device, such as a fluoroscope, ultrasonic screen or CT, which device shows the kidney stone within the kidney so that a needle from outside the body can be forced directly into the collecting system or central cavity of the kidney itself. Following this actual renal puncture, an angiographic wire having a plastic catheter is forced into the kidney. This procedure of a catheter with a wire being directed into the kidney from outside the body is usually performed with local anesthesia; however, it could involve general anesthesia which presents some normal patient difficulty. After a needle has been passed into the kidney and a wire with a plastic catheter is forced through the opening to the kidney, the patient is then placed under a general anesthesia so that progressively larger sizes of catheters can be positioned over the wire extending from outside the patient to inside the kidney. Progressive increasing of the size of the catheters dilates the passageway from the skin to the kidney itself until a large plastic sheath measuring 28-30 French is left in place to provide a passage from outside the patient to the kidney. After this large plastic sheath is positioned by the angiographic wire, the stone in the kidney can be removed manually by instruments such as a wire basket employed in the past for removing stones through the urinary tract. In some instances, a grinding device is used to reduce the size of the stone until it can be removed manually through the plastic sheath remaining in the body. This method is surgical in nature; however, it is preferred over the standard surgical approach because the percutaneous procedure is less injurious to the kidney and less traumatic to the patient. Consequently, the recovery time and discomfort is greatly reduced. Even though this particular medical procedure for removing stones lodged in the kidney is quite an improvement over general surgery, there is some difficulty in that the kidney is punctured. Other organs adjacent the kidney may be inadvertently punctured. Also, the kidney can be ruptured to cause hemorrage or severe trauma to the kidney and to the various organs around the kidney, such as the liver or spleen. These disadvantages are outweighed by the advantages over general surgery in certain instances and this method is employed as generally accepted practice for removing kidney stones.
Referring now to the extracoporeal ultrasonic lithotripsy procedure, the kidney stone lodged in the kidney is eliminated without incisions or catheter penetration of the urinary tract. In this system, a biplane x-ray machine localizes the renal calculi in a particular patient. The patient is then placed in a very large water bath so that the whole body, except the head and neck, is immersed in the water. The patent is then anesthetized, either with a general or spinal anesthesia, and the x-ray machine is used to focus hydraulic shock waves onto the stone within the kidney. After this focusing process, high intensity shock waves are generated in the water bath and these waves are transmitted through the water to the stone within the kidney. This shock wave is applied for a long time, as long as 30 or 40 minutes, which causes disintegration of the stone into relatively small granular pieces that can be passed naturally through the ureter into the bladder and from the bladder in normal bladder function. This medical procedure has become widely publicized and is sought by many patients; however, it involves a device that is very expensive to obtain and extremely expensive to maintain. Each machine will last for a very short time, in the neighborhood of five to six years so that the high cost of the machine must be amortized over a relatively short period. In view of the expense, only a few hospitals can justify purchasing and maintaining this type of a device. Beyond the cost factor, these devices, which are now coming into use, have been found to present some difficulty in attempting to focus the sound wave onto a very small stone located in the inside of the patient. Such a focusing problem requires substantial skill. If the sound waves are not properly focused, the kidney itself and adjacent tissue can be agitated with the resulting trauma. Also, these devices use traditional x-ray machines with the normal radiation concerns and the inability to detect certain stones, such as uric acid stones.
As can be seen, tremendous medical advance has been realized in the area of management of kidney stones for convenient and safe removal. Even with these advances, the latest medical technology has certain disadvantages, such as cost and possible tissue trauma, which bode against universal use of the newly developed techniques.